The Curiosity rover, now in its 158th Mars day on the surface of the red planet, and sitting about a third of a mile from its August landing site, has discovered a very complex history in the Glenelg region it has been investigating. Images have revealed strikingly diverse geologies in the slight depression known as Yellowknife Bay. Curiosity has observed patterns of flat rocks, one of which will be the first drilling target; a small ledge of rocks about sidewalk height that have cracks, that became veins, filled with minerals; and round and rounded spherules, or sedimentary concretions, made of minerals that precipitated out of the water, and became dispersed in the area. One region has parallel and inclined layers, or crossbedding, of sedimentary rocks, laid down by flowing water, similar to those found in outcrops by the earlier Mars rover, Opportunity.

Scientists working on the mission explained that the different sizes of the sand, from tiny grains to small pebbles, reveal clues as to what method transported the material around the planet. Smaller grains could be wind-blown, but larger ones would require a liquid. Dr. John Grotzinger, Project Scientist, explained that differences in the terrain were initially observed from orbit, but the diversity of area surprised the science team.

The first rock drilling experiment, which material will be dumped out to clean the drilling equipment, will be in the John Klein patch of flat rocks. Klein was a former deputy project manager for the mission, who died in 2011. Drilling could being in a few days.

Dr. Grotzinger acknowledged the frustration of the reporters, who have been waiting for Curiosity to start its trek to Mount Sharp, the target of her exploration mission. But he explained that the mission is "100% discovery driven," and the rover will be stopping to do "other interesting things." He said he hoped that Curiosity would make it to Mount Sharp by the end of this year.